.Outermost{ /* 第一小题最外层div */
    width: 1000px;
    height: 600px;
    border: 1px solid navy;
}
/*            ↓↓作业第一小题↓↓             */
.Outermost1{
    position: relative;
    width: 1000px;
    height: 80%;
    border: 1px solid red;
}
.center{
    position: relative;
    top:50%;
    left: 50%;
    width: 500px;
    height: 200px;
    margin-top: -100px;
    margin-left: -250px;
    border: 1px solid green;
}
/*            ↑↑作业第一小题↑↑             */

/*            ↓↓作业第二小题↓↓             */
.Outermost2{
    position: relative;
    width: 1000px;
    height: 500px;
    margin-top: 30px;
    border: 1px solid #AA22FF;
}
.center1{
    position: relative;
    top:50%;
    left: 50%;
    width: 500px;
    height: 200px;
    margin-top: -100px;
    margin-left: -250px;
    border: 1px solid blue;
}
.center2{
    position: relative;
    width: 500px;
    height: 200px;
    margin-top: 150px;
    margin-left: 250px;
    border: 1px solid blue;
}
.center3{
    position: relative;
    top: 150px;
    left: 250px;
    width: 500px;
    height: 200px;
    border: 1px solid blue;
}
.center4{
    position: relative;
    width: 500px;
    height: 200px;
    margin-top: 15%;
    margin-left: 25%;
    border: 1px solid blue;
}
.center5{
    position: relative;
    top:30%;
    left: 25%;
    width: 500px;
    height: 200px;
    border: 1px solid blue;
}
/*            ↑↑作业第二小题↑↑             */